Mechanically actuated fluid infusion device

ABSTRACT

A fluid infusion device, for delivery of a medication fluid to the body of a user, includes a housing, a fluid reservoir for the medication fluid, a dosing mechanism, an infusion component, and a mechanical actuator. The fluid reservoir and the dosing mechanism are located in the housing, and the dosing mechanism is coupled to receive the medication fluid from the fluid reservoir. The dosing mechanism has an adjustable fluid chamber that defines a variable dosage volume. The infusion component is coupled to the dosing mechanism to receive the medication fluid from the adjustable fluid chamber. The mechanical actuator is coupled to the dosing mechanism such that operation of the mechanical actuator causes the medication fluid to be expelled from the adjustable fluid chamber to the infusion component.

TECHNICAL FIELD

Embodiments of the subject matter described herein relate generally tomedical devices such as fluid infusion devices. More particularly,embodiments of the subject matter relate to a low cost, mechanicallyactuated insulin infusion pump.

BACKGROUND

Certain diseases or conditions may be treated, according to modernmedical techniques, by delivering a medication or other substance to thebody of a patient, either in a continuous manner or at particular timesor time intervals within an overall time period. For example, diabetesis commonly treated by delivering defined amounts of insulin to thepatient at appropriate times. Some common modes of providing insulintherapy to a patient include delivery of insulin through manuallyoperated syringes and insulin pens. Other modern systems employprogrammable fluid infusion devices (e.g., insulin pumps) to delivercontrolled amounts of insulin to a patient.

A fluid infusion device suitable for use as an insulin pump may berealized as an external device or an implantable device that issurgically implanted into the body of the patient. External fluidinfusion devices include devices designed for use in a generallystationary location (for example, in a hospital or clinic), and devicesconfigured for ambulatory or portable use (to be carried by a patient).External fluid infusion devices may establish a fluid flow path from afluid reservoir to the patient via, for example, a suitable hollowtubing. The hollow tubing may be connected to a hollow fluid deliveryneedle that is designed to pierce the patient's skin to deliver aninfusion medium to the body. Alternatively, the hollow tubing may beconnected directly to the patient's body through a cannula or set ofmicro-needles.

Portable insulin pump devices can be expensive to procure and maintaindue to their extensive use of sensitive electronic components,batteries, microprocessor chips, electronic display elements, motors,controllers, and the like. Consequently, many diabetes patients continueto use the traditional low cost approach that involves patient-actuatedsyringes. Accordingly, it would be desirable to have a low cost portablefluid infusion pump device that need not rely on expensive electroniccomponents for fluid delivery operations. Furthermore, other desirablefeatures and characteristics will become apparent from the subsequentdetailed description and the appended claims, taken in conjunction withthe accompanying drawings and the foregoing technical field andbackground.

BRIEF SUMMARY OF EMBODIMENTS

An embodiment of a fluid infusion device is disclosed. The fluidinfusion device is designed to deliver a medication fluid to the body ofa user. The fluid infusion device includes a housing, a fluid reservoirfor the medication fluid, a dosing mechanism, an infusion component, anda mechanical actuator. The fluid reservoir and the dosing mechanism areboth located in the housing. The dosing mechanism is coupled to thefluid reservoir to receive the medication fluid from the fluidreservoir. The dosing mechanism includes an adjustable fluid chamberthat defines a variable dosage volume. The infusion component is coupledto the dosing mechanism to receive the medication fluid from theadjustable fluid chamber. The mechanical actuator is also coupled to thedosing mechanism. Operation of the mechanical actuator causes themedication fluid to be expelled from the adjustable fluid chamber to theinfusion component.

Another embodiment of a fluid infusion device is also disclosed. Thefluid infusion device includes a housing, a fluid reservoir for themedication fluid, a valve assembly located in the housing, a dosingmechanism located in the housing, and a fluid conduit. The medicationfluid in the fluid reservoir is maintained under positive pressure. Thevalve assembly is coupled to the fluid reservoir, and the dosingmechanism is coupled to the fluid reservoir via the valve assembly. Thedosing mechanism includes an adjustable fluid chamber that defines auser-selectable dosage volume. The dosing mechanism also includes amechanical actuator. The fluid conduit is coupled to the dosingmechanism via the valve assembly. At least a portion of the fluidconduit is external to the housing when the fluid infusion device isdeployed for operation. Application of an actuation force to themechanical actuator initiates a fluid delivery operation, and removal ofthe actuation force from the mechanical actuator initiates a refilloperation. During the fluid delivery operation, the valve assemblyallows the medication fluid to flow from the adjustable fluid chamberinto the fluid conduit for delivery to the body of the patient, whileinhibiting flow of the medication fluid from the adjustable fluidchamber into the fluid reservoir. During the refill operation, the valveassembly allows the medication fluid to flow from the fluid reservoirinto the adjustable fluid chamber, while inhibiting flow of themedication fluid from the fluid reservoir into the fluid conduit.

Also provided here is an embodiment of a fluid infusion device fordelivery of a medication fluid to the body of a user. The fluid infusiondevice includes a housing, a fluid reservoir to maintain the medicationfluid under positive pressure, wherein the fluid reservoir is located inthe housing, and a valve assembly located in the housing and coupled tothe fluid reservoir. The fluid infusion device also includes a dosingmechanism located in the housing and coupled to the fluid reservoir viathe valve assembly. The dosing mechanism includes a mechanical actuatorto adjust a fluid chamber of the dosing mechanism such that the fluidchamber defines a user-selectable dosage volume. The fluid infusiondevice also includes a fluid delivery conduit coupled to the dosingmechanism via the valve assembly. In response to application of force tothe mechanical actuator, the medication fluid in the fluid chamber isexpelled through the fluid delivery conduit, while the valve assemblyinhibits flow of the medication fluid from the fluid chamber to thefluid reservoir. In response to removal of the force, the mechanicalactuator automatically retracts to refill the fluid chamber with themedication fluid from the fluid reservoir, while the valve assemblyinhibits flow of the medication fluid from the fluid reservoir to thefluid delivery conduit and inhibits fluid flow from the fluid deliveryconduit to the fluid chamber.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the subject matter may be derived byreferring to the detailed description and claims when considered inconjunction with the following figures, wherein like reference numbersrefer to similar elements throughout the figures.

FIG. 1 is a perspective view of an exemplary embodiment of amechanically actuated fluid infusion device;

FIG. 2 is a side view of the fluid infusion device shown in FIG. 1 afterattachment to the body of a user;

FIG. 3 is a perspective view of another exemplary embodiment of amechanically actuated fluid infusion device, shown with an infusion setcomponent;

FIG. 4 is a schematic representation of various components of amechanical fluid infusion device;

FIG. 5 is a simplified schematic side view of an embodiment of apressurized fluid reservoir that cooperates with a force-impartingstructure;

FIG. 6 is a simplified schematic side view of an embodiment of aself-contracting fluid reservoir;

FIG. 7 is a simplified schematic side view of an embodiment of aself-contracting fluid reservoir that resembles a resilient balloon;

FIG. 8 is a simplified schematic side view of an embodiment of apressurized fluid reservoir that employs a spring loaded plunger;

FIG. 9 is a schematic representation of various components of anembodiment of a mechanical fluid infusion device;

FIG. 10 is a perspective top view of an exemplary embodiment of amechanically actuated fluid infusion device, with a portion of itshousing removed;

FIG. 11 is a perspective view of a fluid reservoir suitable for use withthe fluid infusion device shown in FIG. 10, prior to filling with amedication fluid;

FIG. 12 is a perspective view of the fluid reservoir shown in FIG. 11,after filling with the medication fluid;

FIG. 13 is a perspective and partially sectioned view of a dispensingunit suitable for use with the fluid infusion device shown in FIG. 10;

FIG. 14 is an exploded perspective view of the dispensing unit shown inFIG. 13; and

FIGS. 15 and 16 are cross sectional views of the dispensing unit shownin FIG. 13.

DETAILED DESCRIPTION

The following detailed description is merely illustrative in nature andis not intended to limit the embodiments of the subject matter or theapplication and uses of such embodiments. As used herein, the word“exemplary” means “serving as an example, instance, or illustration.”Any implementation described herein as exemplary is not necessarily tobe construed as preferred or advantageous over other implementations.Furthermore, there is no intention to be bound by any expressed orimplied theory presented in the preceding technical field, background,brief summary or the following detailed description.

Certain terminology may be used in the following description for thepurpose of reference only, and thus are not intended to be limiting. Forexample, terms such as “upper”, “lower”, “above”, and “below” may beused to refer to directions in the drawings to which reference is made.Terms such as “front”, “back”, “rear”, “side”, “outboard,” and “inboard”may be used to describe the orientation and/or location of portions of acomponent within a consistent but arbitrary frame of reference which ismade clear by reference to the text and the associated drawingsdescribing the component under discussion. Such terminology may includethe words specifically mentioned above, derivatives thereof, and wordsof similar import. Similarly, the terms “first”, “second” and other suchnumerical terms referring to structures do not imply a sequence or orderunless clearly indicated by the context.

The following description relates to a fluid infusion device of the typeused to treat a medical condition of a patient. The infusion device isused for infusing fluid into the body of a user. The non-limitingexamples described below relate to a medical device used to treatdiabetes (more specifically, an insulin pump), although embodiments ofthe disclosed subject matter are not so limited. Accordingly, theinfused medication fluid is insulin in certain embodiments. Inalternative embodiments, however, many other fluids may be administeredthrough infusion such as, but not limited to, disease treatments, drugsto treat pulmonary hypertension, iron chelation drugs, pain medications,anti-cancer treatments, medications, vitamins, hormones, or the like.For the sake of brevity, conventional features and characteristicsrelated to infusion system operation, insulin pump and/or infusion setoperation, fluid reservoirs, and subcutaneous fluid delivery componentsmay not be described in detail here. Examples of infusion pumps and/orrelated pump drive systems used to administer insulin and othermedications may be of the type described in, but not limited to: UnitedStates patent application number 2009/0299290 A1; United States patentapplication number 2008/0269687; U.S. Pat. No. 7,828,764; and U.S. Pat.No. 7,905,868 (the entire content of these patent documents isincorporated by reference herein).

The subject matter described here relates to various features,components, operating methodologies, and technology associated with amechanical fluid infusion device. The fluid infusion device is“mechanical” in that it need not (and preferably does not) rely on anyelectronic components or power supply to support its primary fluiddelivery operations. In certain exemplary embodiments, the activationand/or actuation of the fluid delivery function is achieved in a fullymechanical manner. Accordingly, an embodiment can be deployed withminimal or no electronic or electrical elements, components, powersources, sensors, motors, or the like. For this reason, a practicalimplementation of the mechanical fluid infusion device can bemanufactured in a very cost efficient manner to provide a low costalternative to the modern electronic and processor based infusiondevices that are currently available. Moreover, the mechanical fluidinfusion device could be designed to be a disposable single-use item,due to its low manufacturing cost.

Turning now to the drawings, FIG. 1 is a perspective view of oneexemplary embodiment of a mechanically actuated fluid infusion device100 prior to deployment, and FIG. 2 is a side view of the fluid infusiondevice 100 after attachment to the body of a user. The fluid infusiondevice 100 includes an outer housing 102 that represents the primarystructural component of the fluid infusion device 100. The housing 102may be fabricated from a lightweight and tough material such as a moldedplastic material. In practice, the housing 102 may be fabricated in twoor more pieces that are assembled to form a shell for various internalcomponents of the fluid infusion device 100. For example, the housing102 may be manufactured in two halves that are bonded, welded, orotherwise attached together to enclose the internal components.

The fluid infusion device 100 includes a mechanical actuator 104 (e.g.,a plunger, a dispensing unit, or the like) that is operated to deliver ametered dose of fluid to the body of the patient. As depicted in FIG. 1,the mechanical actuator 104 may terminate at a knob 106 that protrudesfrom the outer housing 102. For this particular embodiment, the useractuates (e.g., presses down on) the knob 106 to activate the fluiddelivery operation of the fluid infusion device 100. The housing 102 mayincorporate or cooperate with one or more safety features to reduce thelikelihood of accidental fluid delivery. For example, the housing 102may include a locking mechanism for the knob 106 (e.g., a switch, abutton, a slider, or the like) that must be released to actuate the knob106. As another example, the housing 102 may include one or morestructural features that make it difficult for the knob 106 to beinadvertently actuated (e.g., a hood feature, guard tabs surrounding theknob 106, or the like).

Moreover, rotation of the knob 106 adjusts the volume of a fluid chamber(hidden from view in FIG. 1) such that a metered amount of fluid can beadministered with each activation of the mechanical actuator. Thisadjustment feature is described in more detail below with reference toFIGS. 4 and 13-16. In this regard, the fluid infusion device 100 mayinclude a feature that indicates the dosage volume setting to the user.For example, the housing 102 may include a slot, a window, or an opening108 formed therein. After adjusting the dosage volume to the desiredsetting, an identifier of the current volume setting will appear withinthe opening 108. In practice, labels, numbers, color codes, symbols, orany type of indicia can be used for this purpose. For example, the fluidinfusion device 100 may be suitably configured to provide a plurality ofpredetermined and calibrated dosage volumes, such that the desireddosage setting is visible within the opening 108 (e.g., 1 Unit, 5 Units,10 Units, or any quantity or measurement using any convenient orstandardized unit of measure).

The fluid infusion device 100 may also include a fill port 110 that isaccessible from outside the housing 102. The fill port 110 is fluidlycoupled to a fluid reservoir (not visible in FIG. 1) that is locatedinside the housing 102. The fill port 110 is suitably configured tofacilitate filling of the fluid reservoir with the desired fluid, e.g.,a medication fluid such as insulin. Depending upon the embodiment and/orthe desired application, the fill port 110 could be designed toaccommodate filling of the fluid reservoir at the time of manufacture orto accommodate filling (and, in certain implementations, refilling) bythe end user, a caregiver, a physician, or the like. In accordance withone embodiment, the fill port 110 includes a small opening or hole thataccommodates a syringe needle such that a syringe can be used to fillthe internal fluid reservoir. Moreover, the fill port 110 is preferablydesigned to be self-sealing such that the medication fluid does not leakout of the fill port 110 after the internal fluid reservoir has beenfilled. To this end, the fill port 110 may employ a resilient sealingelement (such as a septum) through which the filling needle passesduring the filling operation. In an alternative embodiment designed tobe a single use and disposable unit, the internal fluid reservoir may beprovided in a pre-filled state (filled during manufacturing), renderingthe fill port 110 unnecessary.

The illustrated embodiment of the fluid infusion device 100 is intendedto be affixed to the skin of the patient. Accordingly, the fluidinfusion device 100 may include an adhesive patch 112 or an adhesivelayer having a first side 114 affixed to the housing 102 and having asecond side 116 (see FIG. 2) for attachment to the body of the patient.The second side 116 of the adhesive patch 112 may be provided to theuser with a removable liner (not shown) that is removed and discardedprior to use. Thus, the adhesive patch 112 allows the patient orcaregiver to secure the fluid infusion device 100 to a convenient anddiscreet location on the body of the patient, as desired.

This particular embodiment of the fluid infusion device 100 includes anintroducer 120 (see FIG. 1) that is used to insert a fluid deliveryconduit 122 (see FIG. 2) into the skin of the patient. The fluiddelivery conduit 122 is one suitable embodiment of an infusion componentthat is integrated with the housing 102 to accommodate direct attachmentof the fluid infusion device 100 to the body of the user. The introducer120 may include a needle that facilitates subcutaneous insertion of aflexible fluid delivery conduit 122, e.g., a tube or a cannula. Thus,after the housing 102 is affixed to the skin 124 of the patient, theintroducer 120 can be manipulated to insert the fluid delivery conduit122 into the body of the patient. Accordingly, when the fluid infusiondevice 100 is deployed for operation in this manner, at least a portionof the fluid delivery conduit 122 is external to the housing 102. Theintroducer 120 can be removed and discarded after insertion of the fluiddelivery conduit 122. Accordingly, the introducer 120 does not appear inFIG. 2. After deployment, the fluid delivery conduit 122 functions asone part of the fluid delivery path associated with the fluid infusiondevice 100, as is well understood.

FIG. 3 is a perspective view of another exemplary embodiment of amechanically actuated fluid infusion device 200. The fluid infusiondevice 200 is similar in many respects to the fluid infusion device 100described above. The fluid infusion device 200, however, cooperates withan infusion component 201 that is remote from the housing 202 of thefluid infusion device 200. More specifically, the illustrated embodimentof the infusion component 201 includes an infusion set 204 and tubing206 coupled between the infusion set 204 and the fluid source (notshown) located within the housing 202. The infusion set includes acannula 208 for subcutaneous insertion into the body of the user.Accordingly, the tubing 206 establishes and maintains a fluid flow pathfrom the fluid source to the infusion set 204 and to the cannula 208.The infusion set 204 may include an adhesive element 210 to accommodatedirect attachment of the infusion set 204 to the body of the user. Inpractice, the fluid infusion device 200 could be affixed to the body ofthe patient (as described above for the fluid infusion device 100), orit could be carried or worn by the patient in an appropriate manner(e.g., using a belt clip, in a pocket, or strapped to the body).

FIG. 4 is a schematic representation of various components of anexemplary embodiment of a mechanical fluid infusion device 300 that issuitably configured to deliver a medication fluid to the body of a userin response to user actuation. The components depicted in FIG. 4 may befound in an embodiment of the fluid infusion device 100 (FIG. 1) and inan embodiment of the fluid infusion device 200 (FIG. 3). The illustratedembodiment of the fluid infusion device 300 generally includes, withoutlimitation: a pressurized fluid reservoir 302; a dosing mechanism 304having an adjustable fluid chamber that defines a variable dosagevolume; a subcutaneous fluid conduit 306; a volume or dosage adjuster308; and a mechanical fluid delivery actuator 310. The fluid infusiondevice 300 may also incorporate a suitably configured valve assembly 312having one or more fluid valves to regulate the flow of the medicationfluid throughout the fluid infusion device 300 and to regulate thedelivery of the medication fluid from the fluid infusion device 300. Itshould be appreciated that FIG. 4 represents a simplified functionalrepresentation of the fluid infusion device 300, and that a workingimplementation of the fluid infusion device 300 may (and usually will)include additional elements, components, and structure that is neithershown nor described in detail here. FIG. 4 is presented here to providea foundation for the following description of the general functionalityof the mechanically actuated fluid infusion device 300.

The fluid reservoir 302 may be provided as a pre-filled component, or itmay be designed to accommodate filling by the end user, a caregiver, orthe like. The fluid reservoir 302 holds a quantity of medication fluidand serves as the source of the medication fluid for the fluid infusiondevice 300. For the exemplary embodiments described here, the fluidreservoir 302 is located and held in place in the housing (not shown inFIG. 4) of the fluid infusion device 300. The fluid reservoir 302 ispressurized in that the medication fluid in the fluid reservoir 302 ismaintained under positive pressure using an appropriate methodology,technique, or structure. In other words, the medication fluid is heldunder pressure that would normally force the medication fluid out of thefluid reservoir 302. The valve assembly 312 may include an inlet valve312 a between the fluid reservoir 302 and the dosing mechanism 304,wherein the inlet valve 312 a regulates flow of the medication fluidfrom the fluid reservoir 302 to the dosing mechanism 304. For example,the inlet valve 312 a may be realized as a one-way valve that inhibitsflow of the medication fluid from the adjustable fluid chamber of thedosing mechanism 304 to the fluid reservoir 302.

The dosing mechanism 304 is also located inside the housing of the fluidinfusion device 300, and is coupled to the fluid reservoir 302 toreceive the medication fluid from the fluid reservoir 302 as needed. Thedosing mechanism 304 has an adjustable fluid chamber that can beconfigured and set—by the patient, a caregiver, the manufacturer, thevendor, a physician, or the like—by manipulating the volume adjuster308. The volume adjuster 308 may be realized as one or more knobs,switches, buttons, sliders, levers, etc. In certain embodiments, thedosing mechanism 304 accommodates a plurality of differentuser-selectable and/or calibrated fluid delivery volumes (such as 1Unit, 5 Units, and 10 Units), wherein only the pre-set volumes can beselected. Thus, the adjustable fluid chamber may be adjustable indiscrete steps that define a plurality of predetermined and calibrateddosage volumes for the dosing mechanism 304. In an alternativeembodiment, the dosing mechanism 304 is continuously variable (between aminimum volume and a maximum volume) to provide the user with greaterflexibility and more options. Once adjusted and set, however, the dosingmechanism 304 defines an accurate and metered dose of the medicationfluid.

Each fluid delivery operation results in the delivery of one metereddose, as determined by the adjustable volume of the dosing mechanism304. Thus, if the fluid delivery volume is set at one Unit and thepatient desires to administer a bolus of five Units, then the fluiddelivery actuator 310 must be manipulated five times in succession todeliver a total of five Units. As another example, if the volume is setat five Units, then the fluid delivery actuator 310 must be activatedtwice to deliver a bolus of ten Units. Depending upon the particularimplementation, the fluid delivery actuator 310 may be realized as aswitch, a button, a lever, a plunger, or any suitably configuredmechanical component. In an exemplary embodiment, the fluid deliveryactuator 310 is realized as a mechanical plunger for the adjustablefluid chamber of the dosing mechanism 304.

Operation of the fluid delivery actuator 310 forces the medication fluidout of the fluid chamber of the dosing mechanism 304, and causes themedication fluid to be expelled from the fluid chamber to the fluidconduit 306, which represents one suitable embodiment of an infusioncomponent for the fluid infusion device 300. In this regard, the fluidconduit 306 is coupled to the dosing mechanism 304 to receive themedication fluid from the adjustable fluid chamber as needed. Asmentioned above with reference to FIGS. 1-3, the fluid conduit 306 maybe a rigid needle or a soft cannula that extends directly from thehousing of the fluid infusion device 300, or it may be a rigid needle ora soft cannula associated with an infusion set component that is fluidlycoupled to the fluid infusion device 300 using a tube.

The valve assembly 312 may include an outlet valve 312 b between thedosing mechanism 304 and the fluid conduit 306, wherein the outlet valve312 b regulates flow of the medication fluid from the adjustable fluidchamber of the dosing mechanism 304 to the fluid conduit 306. In thisregard, the outlet valve 312 b may be realized as a one-way valve thatinhibits flow of the medication fluid from the fluid conduit 306 to thedosing mechanism 304. Moreover, the valve assembly 312 may be suitablyconfigured to inhibit flow of the medication fluid from the fluidreservoir 302 directly to the fluid conduit 306. In other words, thevalve assembly 312 may be designed to ensure that fluid from the fluidreservoir 302 must flow into the adjustable fluid chamber of the dosingmechanism 304 before it flows to the fluid conduit 306.

FIG. 4 schematically depicts the dosing mechanism 304, the volumeadjuster 308, and the fluid delivery actuator 310 as distinct functionalelements. In practice, however, the dosing mechanism and the mechanicalfluid delivery actuator 310 could form an integrated subassembly of thefluid infusion device 300. Similarly, the dosing mechanism and thevolume adjuster 308 could be fabricated as an integrated subassembly. Inyet another embodiment, the dosing mechanism 304, the volume adjuster308, and the fluid delivery actuator 310 are realized as a singlecooperating subassembly (as described below with reference to FIGS.9-16).

As mentioned above, the medication fluid may be held under positivepressure to facilitate the fluid delivery action of the fluid infusiondevice. Accordingly, the fluid reservoir may be referred to here as apressurized fluid reservoir. In this regard, a pressurized fluidreservoir can be achieved using a variety of reservoir configurations,as desired for the particular application. For example, FIGS. 5-8schematically depict four different ways in which medication fluid canbe maintained under positive pressure in the context of a fluid infusiondevice of the type described here. These examples are not intended to beexhaustive or to limit the scope and application of the embodimentspresented here. Indeed, a pressurized fluid reservoir could beimplemented using other techniques, components, and structures not shownor described in detail here.

FIG. 5 is a simplified schematic side view of an embodiment of apressurized fluid reservoir 402 that cooperates with a force-impartingstructure 404. For this embodiment, the fluid reservoir 402 is realizedas a resilient and compressible bladder or bag. Therefore, the fluidreservoir 402 could be fabricated from any flexible material that doesnot react with the medication fluid. The fluid reservoir 402 may bepositioned within an interior pocket or cavity formed within the housing406 of the fluid infusion device. The structure 404 is operativelycoupled to the fluid reservoir 402 to impart a compressive force to thefluid reservoir 402. In this regard, the structure 404 may include orcooperate with a spring 408 or any suitable biasing element to form aspring loaded platform for the fluid reservoir 402. In accordance withthis arrangement, the structure 404 (e.g., the spring loaded platform)squeezes the resilient bladder of the fluid reservoir 402 against aninterior surface of the housing 406 such that the external force on thebladder places the medication fluid in the bladder under positivepressure. Accordingly, the medication fluid naturally flows out of thefluid reservoir 402 (in the direction indicated by the arrow) unless theflow is inhibited by the valve assembly of the fluid infusion device. Itshould be appreciated that more than one force imparting structure couldbe deployed to compress the fluid reservoir 402 within the housing 406.Moreover, the direction(s) in which the fluid reservoir 402 iscompressed may vary from one embodiment to another.

FIG. 6 is a simplified schematic side view of an embodiment of aself-contracting fluid reservoir bag 412 that is suitable for use as afluid reservoir for medication fluid. The reservoir bag 412 is realizedas a self-contracting resilient bellows that naturally tends to “shrink”upon itself, as indicated by the opposing horizontal arrows in FIG. 6.Thus, the reservoir bag 412 expands in volume when filled with themedication fluid, and such expansion inherently places the medicationfluid under positive pressure. Accordingly, the medication fluidnaturally flows out of the reservoir bag 412 (in the direction indicatedby the outgoing arrow) unless the flow is inhibited by the valveassembly of the fluid infusion device. Moreover, the reservoir bag 412naturally shrinks as the medication fluid exits.

FIG. 7 is a simplified schematic side view of another embodiment of aself-contracting fluid reservoir bag that is realized as aself-contracting balloon 422. The balloon 422 is similar to thereservoir bag 412 shown in FIG. 6 in that the balloon 422 naturallytends to “shrink” upon itself, as indicated by the inwardly pointingarrows in FIG. 7. Thus, the balloon 422 expands in volume when filledwith the medication fluid, and such expansion inherently places themedication fluid under positive pressure. Accordingly, the medicationfluid naturally flows out of the balloon 422 (in the direction indicatedby the outgoing arrow) unless the flow is inhibited by the valveassembly of the fluid infusion device. Moreover, the balloon 422naturally shrinks as the medication fluid exits.

FIG. 8 is a simplified schematic side view of an embodiment of apressurized fluid reservoir 432 that employs a spring loaded plunger434. The fluid reservoir 432 includes a barrel body 436 (typicallyhaving a cylindrical shape) having a fluid delivery end 438 and a base440 that is opposite the fluid delivery end 438. The plunger 434 islocated in the barrel body 436, and the plunger 434 is suitablyconfigured to travel within the barrel body 436. The fluid reservoir 432also includes a biasing element 442 (e.g., a spring) located in thebarrel body 436 between the plunger 434 and the base 440. In accordancewith this arrangement, the biasing element 442 biases the plunger 434toward the fluid delivery end 438. Movement of the plunger 434 towardthe fluid delivery end 438 causes the medication fluid to be dispensedfrom the fluid reservoir 432.

The biasing element 442 cooperates with the plunger 434 to maintain themedication fluid in the fluid reservoir 432 under positive pressure. Thetension of the biasing element 442 is low enough to allow filling of thefluid reservoir 432 with the medication fluid. In other words, during afill operation the biasing element 442 retracts or compresses to allowthe plunger 434 to move toward the base 440 to accommodate entry of themedication fluid into the fluid reservoir 432. The biasing element 442establishes the positive pressure that causes the medication fluid tonaturally flow out of the fluid reservoir 432 (in the directionindicated by the arrow) unless the flow is inhibited by the valveassembly of the fluid infusion device.

An exemplary implementation of a mechanically actuated fluid infusiondevice employs a pressurized fluid reservoir of the type shown in FIG.8, along with a valve assembly that regulates fluid flow between thepressurized fluid reservoir, a dispensing unit, and a subcutaneous fluidconduit. In this regard, FIG. 9 is a schematic representation of variouscomponents of an embodiment of a mechanical fluid infusion device 500having at least four primary components: a pressurized fluid reservoir502; a dispensing unit 504; a valve assembly 506; and a subcutaneousfluid conduit 508. Some of the features, components, and functionalityof the fluid infusion device 500 are similar (if not identical) to thatdescribed in detail above. For the sake of brevity, common aspects willnot be redundantly described here in the context of the fluid infusiondevice 500.

The pressurized fluid reservoir 502 is physically and fluidly coupled tothe valve assembly 506 to accommodate transfer of the medication fluidfrom the fluid reservoir 502 to the valve assembly 506 as needed. Thedispensing unit 504 is also physically and fluidly coupled to the valveassembly 506 to accommodate transfer of the medication fluid from thevalve assembly 506 to the dispensing unit 504 (as needed), and toaccommodate transfer of the medication fluid from the dispensing unit504 to the valve assembly 506 (as needed). The fluid conduit 508 is alsophysically and fluidly coupled to the valve assembly 506 to accommodatetransfer of the medication fluid from the valve assembly 506 to thefluid conduit 508. In certain embodiments, the valve assembly 506 isfabricated as a single unitary component having three ports (a firstport assigned and coupled to the fluid reservoir 502, a second portassigned and coupled to the dispensing unit 504, and a third portassigned and coupled to the fluid conduit 508). The valve assembly 506is suitably configured to allow or inhibit fluid flow between thecomponents of the fluid infusion device 500 as needed to support thedifferent functions, operations, and states of the fluid infusion device500.

The dispensing unit 504 depicted in FIG. 9 represents a subassembly thatcombines the features and functionality of an adjustable dosingmechanism, a mechanical fluid delivery actuator, and a volume adjuster(as described above with reference to FIG. 4). Accordingly, although notdepicted in FIG. 9, the dispensing unit 504 includes an adjustable fluidchamber that defines a user-selectable dosage volume, wherein the amountof medication fluid in the fluid chamber can be delivered in response tomechanical actuation of an actuator.

The following description assumes that the fluid infusion device 500 isdesigned to accommodate filling of the fluid reservoir 502 by thepatient, a caregiver, a doctor, or another person prior to use (i.e.,the fluid reservoir 502 is not provided as a prefilled unit).Accordingly, a source 512 of the medication fluid can be fluidly coupledto a fill port 513 of the fluid infusion device 500 to fill the fluidreservoir 502 with the desired amount of the medication fluid. A firstflow path 514 represents this filling operation. As explained above withreference to FIG. 8, the fluid reservoir 502 becomes pressurized duringthe filling operation. During the filling operation, the valve assembly506 reacts to certain fluid pressure differentials and reconfiguresitself to inhibit flow of the medication fluid to the fluid conduit 508.In other words, the valve assembly 506 inhibits flow of the medicationfluid from the fluid reservoir 502 such that the fluid source 512 canfill the fluid reservoir 502 in an efficient and safe manner. In certainembodiments, the valve assembly 506 reconfigures itself during thefilling operation to inhibit flow of the medication fluid to thedispensing unit 504. In this regard, the valve assembly 506 inhibitsflow of the medication fluid from the fluid reservoir 502 to theadjustable fluid chamber of the dispensing unit 504 such that the fluidreservoir 502 can be filled in an efficient and safe manner. Inalternative embodiments, the valve assembly 506 reconfigures itselfduring the filling operation to allow the medication fluid to flow tothe dispensing unit 504. In such embodiments, the filling operation mayalso serve to prime at least a portion of the fluid flow path of thefluid infusion device 500. More specifically, during filling the fluidpath between the valve assembly 506 and the fluid conduit 508 is blockedby the valve assembly 506, such that the filling operation primes thefluid pathway except for the segment leading to the fluid conduit 508.This remaining segment can be primed by the user (e.g., by performingone or more fluid delivery actuations) before inserting the fluidconduit 508.

After filling the fluid reservoir 502, filling the fluid chamber of thedispensing unit 504, and priming the flow path of the fluid infusiondevice 500, a user can manually operate the fluid infusion device asneeded to initiate a fluid delivery operation. In response to theapplication of an external force to the mechanical actuator, themedication fluid is expelled from the dispensing unit 504 to flowthrough the valve assembly 506 and through the fluid conduit 508. Asecond flow path 516 represents this fluid delivery operation. Duringthe fluid delivery operation, the valve assembly 506 reacts to certainfluid pressure differentials and reconfigures itself to allow themedication fluid to flow from the adjustable fluid chamber of thedispensing unit 504 into the fluid conduit 508 for delivery to the bodyof the patient, while concurrently inhibiting flow of the medicationfluid from the fluid chamber into the fluid reservoir 502.

Removal of the actuation force from the mechanical actuator of thedispensing unit 504 initiates a refill operation for the fluid infusiondevice 500. For this particular embodiment, when the external force isremoved from the mechanical actuator, the actuator automatically returnsto its nominal position. This action creates a pressure differential inthe flow path, which in turn refills the fluid chamber of the dispensingunit 504 with medication fluid provided by the pressurized fluidreservoir 502. A third flow path 518 represents this refill operation.During the refill operation, the valve assembly 506 reacts to certainfluid pressure differentials and reconfigures itself to allow themedication fluid to flow from the pressurized fluid reservoir 502 intothe fluid chamber of the dispensing unit 504, while concurrentlyinhibiting flow of the medication fluid from the fluid reservoir 502 tothe fluid conduit 508. Moreover, during the refill operation the valveassembly 506 reconfigures itself to inhibit fluid flow from the fluidconduit 508 to the fluid chamber of the dispensing unit 504. Aftercompletion of the refill operation, the fluid chamber of the dispensingunit 504 is ready for the next metered delivery of the medication fluid.

A mechanical fluid infusion device having the features and functionsdescribed above can be implemented and realized in any number of ways,using different platforms and form factors as desired. In this regard,FIGS. 10-16 relate to one exemplary implementation of a mechanicallyactuated fluid infusion device 600. More specifically, FIG. 10 is aperspective top view of the fluid infusion device 600 with a portion ofits housing removed, FIG. 11 is a perspective view of a fluid reservoir602 (in an empty state) of the fluid infusion device 600, FIG. 12 is aperspective view of the fluid reservoir 602 in a filled state, FIG. 13is a perspective and partially sectioned view of a dispensing unit 604of the fluid infusion device 600, FIG. 14 is an exploded perspectiveview of the dispensing unit 604, FIG. 15 is a cross sectional view ofthe dispensing unit 604 in its nominal state prior to adjustment, andFIG. 16 is a cross sectional view of the dispensing unit 604 in itsnominal state after adjustment. It should be appreciated that the fluidinfusion device 600 is similar to the fluid infusion device 100described above with reference to FIG. 1 and FIG. 2. Accordingly,certain features, functions, and aspects that are common to the fluidinfusion devices 100, 600 will not be redundantly described here.

The fluid infusion device 600 includes a housing 606 to enclose andprotect the internal components. For ease of illustration, the housing606 in FIG. 10 is shown in cross section. The housing 606 may include orcooperate with certain internal features 607 a, 607 b that are designedto maintain the internal components of the fluid infusion device 600 inposition and/or to provide structural rigidity to the housing 606. Theskin-facing side of the fluid infusion device 600 may be coupled to anadhesive patch 608 that accommodates attachment to the skin of thepatient.

The fluid infusion device 600 generally includes at least the followingfunctional components: the fluid reservoir 602; the dispensing unit 604;an introducer 612 for a fluid delivery conduit (not shown in FIG. 10); avalve assembly 614; and a fill port 616. As described above withreference to FIG. 9, the valve assembly 614 fluidly and mechanicallycouples together the fluid reservoir 602, the dispensing unit 604, andthe fluid delivery conduit. Although not labeled in FIG. 10, the valveassembly 614 includes or cooperates with suitably shaped and configuredconduits that route the respective fluid flow paths between thecomponents. In certain embodiments, the valve assembly 614 may berealized as a three-way valve having an internal ball that moves inresponse to fluid pressure differentials to regulate the incoming andoutgoing fluid flow paths as needed. The fill port 616 is fluidly andstructurally coupled to the fluid reservoir 602 via a filling conduit620.

Referring to FIG. 11 and FIG. 12, the fluid reservoir 602, the fill port616, and the filling conduit 620 are depicted in an isolated manner. Theillustrated embodiment of the fluid reservoir 602 is a self-pressurizingunit that is similar to the fluid reservoir 432 described above withreference to FIG. 8. FIG. 11 shows the fluid reservoir 602 in an emptystate, and FIG. 12 shows the fluid reservoir 602 in a filled state. Inthe empty state, a spring 622 (or any suitable biasing element) forces aplunger 624 upward and toward an outlet port 626 of the fluid reservoir602. In accordance with one exemplary filling operation, a needle of afilling source can be inserted into the fill port 616 (as indicated bythe arrow 630 in FIG. 11) such that the medication fluid can be forcedunder pressure into a chamber 632 of the fluid reservoir 602. The fillport 616 may include a septum or other type of sealing element thataccommodates the fill needle and forms a fluid seal after the fillneedle is removed. As shown in FIG. 12, the chamber 632 may be definedas the space between the top of the plunger 624 and the outlet port 626.The filling conduit 620 may terminate at an opening 634 that is locatedabove the plunger 624 when the fluid reservoir 602 is in the emptystate. Consequently, the medication fluid fills the chamber 632, whileurging the plunger 624 downward and toward a base 636 of the fluidreservoir 602. During the filling operation, the spring 622 becomescompressed, which in turn pressurizes the fluid reservoir 602 tomaintain the medication fluid under positive pressure. The spring 622preferably keeps the medication fluid under constant pressure until thechamber 632 is empty (or near empty) for practical purposes. Uponcompletion of the filling operation, the needle is removed from the fillport 616 such that the fluid infusion device 600 can be prepared foruse.

The dispensing unit 604 may be coupled to the valve assembly 614 via adispensing conduit 640 (see FIG. 10). For this particular embodiment,the dispensing unit 604 represents a subassembly that incorporates thestructure and functionality of an adjustable fluid chamber, a dosingmechanism, a mechanical delivery actuator, and a volume adjuster for theadjustable fluid chamber. FIGS. 13-16 depict an exemplary embodiment ofthe dispensing unit 604 in greater detail.

The illustrated embodiment of the dispensing unit 604 includes, withoutlimitation: a reservoir barrel 702; a fitting 704 for the reservoirbarrel 702; a plunger stopper 706; a dosage guide 708; a dosage knob710; a spring 712 (or other suitable biasing element); and an actuatorstem 714, which may include, cooperate with, or be coupled to anactuation knob 716. These elements of the dispensing unit 604 arecoupled together or otherwise cooperate with one another to form asubassembly having the desired features and functionality describedhere.

The reservoir barrel 702 forms a part of the adjustable fluid volumethat holds the desired metered amount of medication fluid for deliveryto the patient. In certain embodiments, the reservoir barrel 702 mayhave a cylindrical cross section, and it may resemble the end portion ofa syringe. The reservoir barrel 702 may terminate at a port 722, whichin turn may be coupled to the fitting 704. The fitting 704 cooperateswith the port 722 to establish a physical and fluid connection betweenthe dispensing unit 604 and the valve assembly 614 (see FIG. 10).Although not shown, the fitting 704 may employ a hollow needle thatpierces a septum 724 located in the port 722, wherein the hollow needleestablishes a fluid flow path to and from the interior of the reservoirbarrel 702.

The dosage guide 708 may be affixed to a base 730 of the reservoirbarrel 702, as shown in FIGS. 13, 15, and 16. For example, the rim ofthe dosage guide 708 could be glued, bonded, welded, or otherwisesecured to the base 730 of the reservoir barrel 702 to form anintegrated component. As shown in FIG. 14, the dosage guide 708resembles a ring with internal threads 732. The internal threads 732mate with and engage corresponding external threads 734 formed on thedosage knob 710. The purpose and function of this threaded engagementare described in more detail below with reference to FIGS. 15 and 16.

The dosage knob 710 includes a longitudinal opening 738 formed thereinto receive and accommodate the actuator stem 714. The longitudinalopening 738 is formed completely through the dosage knob 710 to allowpassage of the actuator stem 714 (see FIGS. 15 and 16). Notably, thedosage knob 710 and the actuator stem 714 are cooperatively configuredto accommodate translation of the actuator stem 714 relative to thedosage knob 710, while inhibiting rotation between the dosage knob 710and the actuator stem 714. Thus, the actuator stem 714 is free to slidewithin the dosage knob 710 between a nominal position and an actuatedposition. However, rotation of the actuator stem 714 results in acorresponding rotation of the dosage knob 710, and vice versa. Theillustrated embodiment achieves this functionality with a key/keywayarrangement. In this regard, the longitudinal opening 738 may define oneor more keyways 740 that receive and cooperate with one or morecounterpart keys 742 that protrude from the actuator stem 714. Althoughnot always required, the embodiment described here employs four keyways740 and four cooperating keys to inhibit rotation of the actuator stem714 relative to the dosage knob 710. The keyway/key arrangement issuitably designed to allow translational movement of the actuator stem714 within the longitudinal opening 738 of the dosage knob 710.

The actuator stem 714 terminates at a plunger end 746 that is suitablyconfigured to mate with and couple to the plunger stopper 706. Incertain embodiments, the plunger end 746 is threaded to mate withcorresponding threads of the plunger stopper 706. The illustratedembodiment employs an externally threaded plunger end 746 that screwsinto an internally threaded cavity (not shown) of the plunger stopper706. FIGS. 13, 15, and 16 depict the dispensing unit 604 after theplunger stopper 706 has been screwed onto the actuator stem 714.

The spring 712 is installed over the actuator stem 714 such that itremains positioned between the actuation knob 716 and an end 750 of thedosage knob 710. When the dispensing unit 604 is assembled, the spring712 serves as a biasing element for the mechanical actuator, such thatthe spring 712 biases the actuator stem 714 and the plunger stopper 706into a nominal pre-delivery position (see FIG. 13 and FIG. 16). Inpractice, the spring 712 is compressed during a fluid delivery strokesuch that it automatically springs back and moves the actuator stem 714back into the nominal pre-delivery position following each operation ofthe mechanical actuator.

The dispensing unit 604 may be assembled in the following manner. Thespring 712 is placed onto the actuator stem 714, followed by the dosageknob 710. The dosage guide 708 is threaded onto the dosage knob 710(either before or after the dosage knob 710 is placed onto the actuatorstem 714, as desired). Next, the plunger stopper 706 is threaded ontothe actuator stem 714 (and, if necessary, glued or otherwise affixed tothe plunger stopper 706). It may be necessary to move the actuator stem714 and compress the spring 712 somewhat to expose the plunger end 746of the actuator stem 714 before attaching the plunger stopper 706 to theplunger end 746. Thereafter, the plunger stopper 706 can be introducedinto the reservoir barrel 702, and the rim of the dosage guide 708 canbe affixed to the base 730 of the reservoir barrel 702, resulting in thearrangement shown in FIGS. 13, 15, and 16.

As explained above, the dispensing unit 604 can be manipulated to varythe volume of an adjustable fluid chamber 760 (see FIG. 13 and FIG. 16).FIG. 15 depicts the state of the dispensing unit 604 with a minimumvolume defined for the adjustable fluid chamber 760, and FIG. 16 depictsthe state of the dispensing unit 604 with a maximum volume defined forthe adjustable fluid chamber 760. For this particular embodiment, theuser-selectable dosage volume is adjusted in response to rotation of theactuator stem 714 and/or rotation of the actuation knob 716. Suchrotation corresponds to rotation of the actuator stem 714 about itsmajor longitudinal axis. Referring to FIGS. 13, 15, and 16, rotation ofthe actuation knob 716 results in rotation of the actuator stem 714,which in turn results in rotation of the dosage knob 710. Rotation ofthe dosage knob 710 causes the dosage knob 710 to translate relative tothe dosage guide 708 (the translation is depicted in FIG. 15 and FIG.16). Translational movement of the dosage knob 710 alters the nominalpre-delivery and post-delivery position of the plunger stopper 706,which in turn changes the nominal pre-delivery and post-delivery dosagevolume of the fluid chamber 760. Notably, the force imparted by thespring 712 causes the actuation knob 716 to be biased away from the end750 of the dosage knob 710, and this biasing action sets the actuatorstem 714 and the plunger stopper 706 into the desired position thatdefines the fluid chamber 760.

The dispensing unit 604 is actuated in response to the application offorce in a direction that is aligned with the major longitudinal axis ofthe actuator stem 714. In practice, the dispensing unit 604 is actuatedwhen the user presses the actuation knob 716 down. Fully depressing theactuator stem 714 results in the delivery of the metered and calibratedamount of medication fluid contained in the fluid chamber 760. Asexplained previously, the fluid reservoir 602 (see FIG. 10)automatically refills the adjustable fluid chamber 760 with themedication fluid in response to the spring 712 returning the actuatorstem 714 into the nominal pre-delivery position.

In certain embodiments, the dispensing unit 604 is designed to providetactile and/or audible feedback to the user while the fluid chamber 760is being adjusted. For example, the dispensing unit 604 may employdetents or tabs to provide “clicks” or other feedback that indicates apredefined volume graduation, e.g., 0.2 Units, 0.5 Units, or 1.0 Unitper click. Thus, adjustment of the dosage volume can be easily achievedby counting the number of clicks as the actuation knob 716 is beingrotated (assuming that the adjustment operation begins at a knownreference volume). Moreover, numerical or other indicia could be printedon the dosage knob 710 and/or elsewhere to indicate the dosage volumeduring the adjustment operation. As described above with reference toFIG. 1, the housing 102 may include an opening 108 that allows the userto see the volume indicator(s) during the adjustment operation.

The dispensing unit 604 may also include a feature that locks theadjustment component(s) to inhibit rotation of the actuator stem 714after the desired dosage volume has been selected. Accordingly, onceset, the metered dosage volume remains fixed until the user or caregiveradjusts the volume again. Thereafter, the medication fluid can bedelivered in metered increments by activating the actuation knob 716,until the medication fluid is depleted. At that time, the entire fluidinfusion device can be discarded. In certain alternative embodiments,the fluid reservoir can be refilled via the fill port to extend theuseful life of the fluid infusion device.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or embodiments described herein are not intended tolimit the scope, applicability, or configuration of the claimed subjectmatter in any way. Rather, the foregoing detailed description willprovide those skilled in the art with a convenient road map forimplementing the described embodiment or embodiments. It should beunderstood that various changes can be made in the function andarrangement of elements without departing from the scope defined by theclaims, which includes known equivalents and foreseeable equivalents atthe time of filing this patent application.

What is claimed is:
 1. A fluid infusion device for delivery of amedication fluid to the body of a user, the fluid infusion devicecomprising: a housing; a fluid reservoir for the medication fluid,wherein the fluid reservoir is located in the housing, and wherein themedication fluid in the fluid reservoir is maintained under positivepressure; a valve assembly located in the housing and coupled to thefluid reservoir; a dosing mechanism located in the housing and coupledto the fluid reservoir via the valve assembly, the dosing mechanismcomprising an adjustable fluid chamber that defines a user-selectabledosage volume, and the dosing mechanism comprising a mechanicalactuator; and a fluid conduit coupled to the dosing mechanism via thevalve assembly, wherein at least a portion of the fluid conduit isexternal to the housing when the fluid infusion device is deployed foroperation; wherein: application of an actuation force to the mechanicalactuator initiates a fluid delivery operation; removal of the actuationforce from the mechanical actuator initiates a refill operation; duringthe fluid delivery operation, the valve assembly allows the medicationfluid to flow from the adjustable fluid chamber into the fluid conduitfor delivery to the body of the patient, while inhibiting flow of themedication fluid from the adjustable fluid chamber into the fluidreservoir; and during the refill operation, the valve assembly allowsthe medication fluid to flow from the fluid reservoir into theadjustable fluid chamber, while inhibiting flow of the medication fluidfrom the fluid reservoir into the fluid conduit.
 2. The fluid infusiondevice of claim 1, wherein: the valve assembly inhibits flow of themedication fluid from the fluid conduit to the fluid reservoir; and thevalve assembly inhibits flow of the medication fluid from the fluidconduit to the adjustable fluid chamber.
 3. The fluid infusion device ofclaim 1, wherein the fluid reservoir comprises a self-contractingreservoir bag.
 4. The fluid infusion device of claim 1, wherein thefluid reservoir comprises: a resilient bladder; and a structureoperatively coupled to the resilient bladder to impart a compressiveforce to the resilient bladder.
 5. The fluid infusion device of claim 1,wherein the fluid reservoir comprises: a barrel body having a fluiddelivery end and a base opposite the fluid delivery end; a plungerlocated in the barrel body; and a biasing element located in the barrelbody between the plunger and the base of the barrel body, wherein thebiasing element biases the plunger toward the fluid delivery end.
 6. Thefluid infusion device of claim 1, wherein the adjustable fluid chamberis adjustable in discrete steps that define a plurality of predeterminedand calibrated dosage volumes.
 7. The fluid infusion device of claim 1,further comprising an adhesive patch having a first side affixed to thehousing and a second side for attachment to the body of the patient. 8.The fluid infusion device of claim 1, further comprising a fill portaccessible from outside the housing, wherein: the fill port is fluidlycoupled to the fluid reservoir to facilitate filling of the fluidreservoir with the medication fluid during a filling operation; andduring the filling operation, the valve assembly inhibits flow of themedication fluid from the fluid reservoir to the fluid conduit.
 9. Afluid infusion device for delivery of a medication fluid to the body ofa user, the fluid infusion device comprising: a housing; a fluidreservoir to maintain the medication fluid under positive pressure,wherein the fluid reservoir is located in the housing; a valve assemblylocated in the housing and coupled to the fluid reservoir; a dosingmechanism located in the housing and coupled to the fluid reservoir viathe valve assembly, the dosing mechanism comprising a mechanicalactuator to adjust a fluid chamber of the dosing mechanism such that thefluid chamber defines a user-selectable dosage volume; and a fluiddelivery conduit coupled to the dosing mechanism via the valve assembly;wherein: in response to application of force to the mechanical actuator,the medication fluid in the fluid chamber is expelled through the fluiddelivery conduit, while the valve assembly inhibits flow of themedication fluid from the fluid chamber to the fluid reservoir; and inresponse to removal of the force, the mechanical actuator automaticallyretracts to refill the fluid chamber with the medication fluid from thefluid reservoir, while the valve assembly inhibits flow of themedication fluid from the fluid reservoir to the fluid delivery conduitand inhibits fluid flow from the fluid delivery conduit to the fluidchamber.
 10. The fluid infusion device of claim 9, wherein theuser-selectable dosage volume is adjustable in discrete steps thatdefine a plurality of predetermined and calibrated dosage volumes. 11.The fluid infusion device of claim 9, wherein: the user-selectabledosage volume is adjusted in response to rotation of the mechanicalactuator about a major longitudinal axis; and the mechanical actuator isactuated in response to application of the force in a direction alignedwith the major longitudinal axis.
 12. The fluid infusion device of claim9, wherein the fluid reservoir comprises a self-contracting reservoirbag.
 13. The fluid infusion device of claim 9, wherein the fluidreservoir comprises: a resilient bladder; and a structure operativelycoupled to the resilient bladder to impart a compressive force to theresilient bladder.
 14. The fluid infusion device of claim 9, wherein thefluid reservoir comprises: a barrel body having a fluid delivery end anda base opposite the fluid delivery end; a plunger located in the barrelbody; and a biasing element located in the barrel body between theplunger and the base of the barrel body, wherein the biasing elementbiases the plunger toward the fluid delivery end.
 15. The fluid infusiondevice of claim 9, further comprising an adhesive patch having a firstside affixed to the housing and a second side for attachment to the bodyof the patient.